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1986 Corvette bogs down

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Old Jun 24, 2010 | 01:23 AM
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Default 1986 Corvette bogs down

I have an 86 Vette with 26,000 miles on it. When the car is cold it runs great. But as soon as it warms up it starts to run not so good. When its warmed up and i give it gas while I'm driving it it bogs down. But when I first run it and the engine is cold it will not do this it runs great. Also when the car is in park and I rev the engine even when warmed up it seems to run great. It is just when the engine is warmed up and I'm driving it that it bogs down when you give it to much gas. I have replaced the fuel pump and filter on it and also ECM is new. I have also put a new catalytic converter, but the problem still remains. I get no check engine warnings either so I really don't know what it could be. Maybe a bad MAF. Any help will be appreciated. Thanks.
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Old Jun 24, 2010 | 08:52 AM
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Have you done any fuel pressure tests ?
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Old Jun 24, 2010 | 11:42 AM
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Sounds like something is happening when the car goes into closed loop. Any codes?
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Old Jun 24, 2010 | 12:11 PM
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Originally Posted by Paul Ruggeri
Sounds like something is happening when the car goes into closed loop. Any codes?
Only 2 things left that I can think of. FP regulator & injectors. Check fuel pressure. Call Jon at FIC for injectors.
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Old Jun 24, 2010 | 05:25 PM
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I have not checked the fuel pressure but since its a closed loop problem could it be a bad oxygen sensor. I'll get back with injector report. Thanks for the advice.
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Old Jun 24, 2010 | 08:46 PM
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fuel injectors
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Old Jun 26, 2010 | 01:39 AM
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Got a code of 43 so gonna replace the knock sensor. Does any one know where it is located? Thanks for the help
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Old Jun 26, 2010 | 03:07 AM
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on the passenger side of the motor on the block between exhaust manifold runners , there are 2 i think the top one is a coolant bottom is knock . they say its easier to get at from the bottom of car. and use sum vise grips on the round part at the same time as u crank on the bolt. it helps it come out in 1 piece
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Old Jun 26, 2010 | 04:54 AM
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When you remove the knock sensor you will lose your coolent just be ready for it
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Old Jun 26, 2010 | 08:08 AM
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Before you throw any money at it, diagnose the 43.

http://members.shaw.ca/corvette86/Code%2043.pdf
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Old Jun 26, 2010 | 08:13 AM
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Originally Posted by AGENT 86
Before you throw any money at it, diagnose the 43.

http://members.shaw.ca/corvette86/Code%2043.pdf
Secret Agent man is correct again.
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Old May 22, 2011 | 11:19 PM
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Originally Posted by marrober9
I have an 86 Vette with 26,000 miles on it. When the car is cold it runs great. But as soon as it warms up it starts to run not so good. When its warmed up and i give it gas while I'm driving it it bogs down. But when I first run it and the engine is cold it will not do this it runs great. Also when the car is in park and I rev the engine even when warmed up it seems to run great. It is just when the engine is warmed up and I'm driving it that it bogs down when you give it to much gas. I have replaced the fuel pump and filter on it and also ECM is new. I have also put a new catalytic converter, but the problem still remains. I get no check engine warnings either so I really don't know what it could be. Maybe a bad MAF. Any help will be appreciated. Thanks.
This describes my problem to an absolute tee! Unfortunately, I still have not found my solution. I've replaced my fuel filter, fuel relay (code 54), cap, rotor, ignition coil, ignition control module, O2 sensor, plugs and wires. My timing was off so set correctly. I've ran the car with the MAF sensor unplugged and it still bogs once it goes into closed loop.

Did you ever figure out your problem? Does anyone have any ideas or experience with this issue?

Thanks!!!

Last edited by Tony A.; May 22, 2011 at 11:22 PM.
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Old May 23, 2011 | 12:17 AM
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Old May 23, 2011 | 01:39 PM
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I'd say fuel injectors too. The early C4 Multecs are junk. I don't care if it has only 26K on it. Once we replaced them with the rebuilt injectors from FIC, the 87' ran totally different. And even if it doesn't, when you fix, what you fix, the car will run much better. There are many of us who've done the injector swap and it works!
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Old May 23, 2011 | 10:12 PM
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If you can believe it my Vette still runs bad. I don't know the last thing to try is injectors. I had my ecm replaced so maybe their is a wiring issue. I replaced my knock sensor to no avail. The times when it does run right it's amazing. I'll keep you up to date. By the way is it possible that there could be rust in the gas tank even though it's made of rubber?
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Old May 23, 2011 | 10:59 PM
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Originally Posted by marrober9
If you can believe it my Vette still runs bad. I don't know the last thing to try is injectors. I had my ecm replaced so maybe their is a wiring issue. I replaced my knock sensor to no avail. The times when it does run right it's amazing. I'll keep you up to date. By the way is it possible that there could be rust in the gas tank even though it's made of rubber?
I have a bunch of people telling me to replace the fuel pump, sock, filter again as my fuel pump relay was causing low voltage and that heats up the pump, making it fail. Looks like I can do it all for under $100 so worth a try.

Good luck with your issues. If you ever figure yours out, let me know. I will do the same.
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Old May 24, 2011 | 12:20 PM
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Originally Posted by marrober9
If you can believe it my Vette still runs bad. I don't know the last thing to try is injectors. I had my ecm replaced so maybe their is a wiring issue. I replaced my knock sensor to no avail. The times when it does run right it's amazing. I'll keep you up to date. By the way is it possible that there could be rust in the gas tank even though it's made of rubber?
The gas tank is made of steel. You might also check all the vacuum lines too, as that will cause a car to run bad. Injectors can't hurt. You'd be surprised at how many early C4's suffer from the crappy multecs. We know, we replaced ours with the FIC's and it runs waa-ay better!
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Old May 24, 2011 | 10:47 PM
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Originally Posted by marrober9
If you can believe it my Vette still runs bad. I don't know the last thing to try is injectors. I had my ecm replaced so maybe their is a wiring issue. I replaced my knock sensor to no avail. The times when it does run right it's amazing. I'll keep you up to date. By the way is it possible that there could be rust in the gas tank even though it's made of rubber?
I got mine working today, finally! She runs like new, lots of power, no bogging.

I replaced my fuel pump and fuel sock. Took all of 30 mins and $90, going with AC Delco parts. I've been struggling with this for 6 weeks and finally got into the tank. It had a lot of small debris. I cleaned out what I could and put in the new parts and BAM, it works!

Good luck finding your issue.
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Old May 25, 2011 | 05:43 AM
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What do the FIC Injectors run?
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